Proposals to incorporate marriage rites used by same-sex couples into the Book of Common Prayer (BCP) of the Episcopal Church in the United States will increase pressure in the Church of England to "dissociate" itself, the secretary general of the Archbishops' Council, William Nye, has warned.

In a letter to the Episcopal Church's Task Force on the Study of Marriage, which has produced the proposals, Mr Nye writes that, if the rites -- written to be used by same-sex or opposite-sex couples -- are incorporated into the BCP as the only marriage rite, "the pressure to dissociate the Church of England from TEC (The Episcopal Church), in all manner of ways, would increase". Such a move would also be "potentially damaging" to work in the CofE to create a new teaching document on sexuality (News, 30 June), he writes.

He goes on to warn that, if provision is not made for traditionalists in The Episcopal Church, it would be a "serious blow for interfaith relations, negatively impacting Christians around the world especially in areas where they are persecuted minorities, as well as harming the stringent efforts to reinforce moderation in religious expression in countries like ours which are affected by terrorism". The Episcopal Church's promulgation of the new liturgies is, he writes, "at the least, unhelpful to those of us seeking to bring the Church of England's deliberations to a good outcome".

The letter was written in response to a consultation by the Task Force, begun in September, which asked every province of the Anglican Communion: "From your perspective and specific setting, what has been the impact of The Episcopal Church's authorization and use of liturgical rites for same-sex marriage and the blessing of same-sex unions on 'the Church'?" The rites were approved for trial use at the Episcopal Church's General Convention in 2015, which also made the canonical definition of marriage gender-neutral (News, 5 July 2015).

Since then, the Task Force has produced proposals, set to be put before the General Convention in July, to add the rites to the BCP, and to amend its other marriage rites, prefaces, and sections of the Catechism to make language gender-neutral (News, 25 August). It outlines how the Convention could make these additions and revisions permanent.

Seven provinces responded to the consultation, of which six said that the rites had had a negative impact, or that they did not approve of same-sex marriage. The Scottish Episcopal Church's response outlined how its own provision for same-sex marriage had been made without a new definition being made explicit in the Code of Canons: "In this respect, the SEC has rejected the approach of TEC."

The response from the Primate of Tanzania, the Most Revd Jacob Erasto Chimeledya, reads: "From now onward be informed that we are not having any church partnership. Please do not write me back on this matter."

Mr Nye's response was by far the longest, running to eight pages. His letter, sent on 18 October, and now available online, emphasises that the time frame for consultation (five weeks) precluded discussion in the C of E's formal deliberative structures; his response "reflects discussions among staff of the Church's Archbishops' Council only".

It states that, "for a majority in the Communion, and in the Church of England, Holy Scripture is held to rule that sexual activity outside marriage between a man and a woman is contrary to God's will".

A long section concerns the 2015 marriage rite's replacement of "procreation of children" with "when it is God's will, for the gift of children", as a purpose of marriage.

"The best one can say about effectively erasing one of the key traditional purposes of marriage is that it is a very big step to have taken unilaterally in the face of global understandings of our shared traditions across the Church of God," Mr Nye writes. "Will the celebrant solemnly repeat the wording of the preface . . . for same-sex and opposite-couples alike, knowing that significantly different understandings of how that gift can be realised are in play? Will there be official, or tacit, agreement to dispense with those lines when a couple is uninterested in God's gift of children, thus colluding with the consumerist assumption that children are a choice not a gift?"

Retaining the rites on a trial basis "might be the least damaging to wider Anglican relationships", he suggests. Another option might be incorporating them as alternatives in the Prayer Book, alongside the existing rite. The letter warns that the Episcopal Church could face "calls for more, and more stringent, consequences" if it authorises new rites (News, 15 January 2016).

He writes: "It is a source of great regret -- shared by many in the Church of England, including many who are deeply sympathetic to LGBTI+ people -- that this step has been taken by TEC without a much wider consensus across the Communion and among our ecumenical partners.

"Whatever the formal consequences which may follow for TEC in relation to the Communion, the introduction of these new liturgies cannot but hinder, in numerous small ways, the good relationships and close cooperation between our two Provinces for which we in the Church of England pray daily. We will watch with considerable interest and some concern to see how the new rites are introduced into the pastoral life of TEC."

While the vast majority -- 93 of 101 -- of bishops in The Episcopal Church have authorised use of the new rites, eight have not, including the Bishop of Springfield, the Rt Revd Daniel Martins. In a blog published last month, he pointed out that, while a diocesan bishop could decline to permit use of a trial rite, he or she could not proscribe use of material in the BCP: "If the events following 2003 were an earthquake, approval of anything like the Taskforce on Marriage's proposal would be a catastrophic aftershock."

The proposals for the Prayer Book are among a set of resolutions that the Task Force drafted for this year's Convention. It has produced two liturgies for blessing the relationships of couples who choose not to marry for legal or financial reasons, and recommended that resources be developed to provide guidance for the rising number of people "in sexually intimate relationships other than marriage".

Its report says that "when it comes to nuanced and sensitive guidance and teaching regarding sexual intimacy, many people feel largely alone, having found the Church's counsel to remain sexually abstinent outside of marriage, insufficient and unreflective of their experience of the holy in relationship."

With the exception of a minority report by Canon Jordan Hylden, Canon Theologian of the diocese of Dallas, appended to its main report, the Task Force appears undeterred by responses to its Communion consultation.

"There are those in our wider Anglican family who will disagree with any changes we make to be more inclusive, and there will be those in our wider Anglican family who are watching us for leadership to help them move forward with similar changes," a Q & A reads.

"The climate in the Anglican Communion has improved dramatically in recent years and we believe the ties that bind us are stronger than the differences that challenge us."